![\"\"](\"https:\/\/cdn.arstechnica.net\/wp-content\/uploads\/2024\/05\/orion-char.jpg\")
<\/p>\n
The inspector general\u2019s report on May 1 included new images of Orion\u2019s heat shield.<\/p>\n
Credit:
\n NASA Inspector General<\/p>\n<\/figure>\n
\u201cBased on the data, we have decided\u2014NASA unanimously and our decision-makers\u2014to move forward with the current Artemis II Orion capsule and heat shield, with a modified entry trajectory,\u201d Bill Nelson, NASA\u2019s administrator, said Thursday. The heat shield investigation and other issues with the Orion spacecraft will now delay the Artemis II launch until April 2026, a slip of seven months from the previous launch date in September 2025.<\/p>\n
Notably the chair of the IRT, a former NASA flight director named Paul Hill, was not present at Thursday\u2019s news conference. Nor did the space agency release the IRT\u2019s report on its recommendations to NASA.<\/p>\n
In an interview, Camarda said he knew two people on the IRT who dissented from its conclusions that NASA\u2019s plan to fly the Orion heat shield, without modifications to address the charring problem, was acceptable. He also criticized the agency for not publicly releasing the independent report. \u201cNASA did not post the results of the IRT,\u201d he said. \u201cWhy wouldn\u2019t they post the results of what the IRT said? If this isn\u2019t raising red flags out there, I don\u2019t know what will.\u201d<\/p>\n
The view from the IRT<\/h2>\n
Ars took these concerns to NASA on Friday, and the agency responded by offering an interview with Paul Hill, the review team\u2019s chair. He strongly denied there were any dissenting views.<\/p>\n
,<\/p>\n
\u201cEvery one of our conclusions, every one of our recommendations, was unanimously agreed to by our team,\u201d Hill said. \u201cWe went through a lot of effort, arguing sentence by sentence, to make sure the entire team agreed. To get there we definitely had some robust and energetic discussions.\u201d<\/p>\n
Hill did acknowledge that, at the outset of the review team\u2019s discussions, two people were opposed to NASA\u2019s plan to fly the heat shield as is. \u201cThere was, early on, definitely a difference of opinion with a couple of people who felt strongly that Orion\u2019s heat shield was not good enough to fly as built,\u201d he said.<\/p>\n
However, Hill said the IRT was won over by the depth of NASA\u2019s testing and the openness of agency engineers who worked with them. He singled out Luis Saucedo, a NASA engineer at NASA\u2019s Johnson Space Center who led the agency\u2019s internal char loss investigation.<\/p>\n
\u201cThe work that was done by NASA, it was nothing short of eye-watering, it was incredible,\u201d Hill said.<\/p>\n
At the base of Orion, which has a titanium shell, there are 186 blocks of a material called Avcoat individually attached to provide a protective layer that allows the spacecraft to survive the heating of atmospheric reentry. Returning from the Moon, Orion encounters temperatures of up to 5,000\u00b0 Fahrenheit (2,760\u00b0 Celsius). A char layer that builds up on the outer skin of the Avcoat material is supposed to ablate, or erode, in a predictable manner during reentry. Instead, during Artemis I, fragments fell off the heat shield and left cavities in the Avcoat material.<\/p>\n
Work by Saucedo and others, including substantial testing in ground facilities, wind tunnels, and high-temperature arc jet chambers, allowed engineers to find the root cause of gases getting trapped in the heat shield and leading to cracking. Hill said his team was convinced that NASA successfully recreated the conditions observed during reentry and were able to replicate during testing the Avcoat cracking that occurred during Artemis I.<\/p>\n
,<\/p>\n
When he worked at the agency, Hill played a leading role during the investigation into the cause of the loss of space shuttle Columbia<\/em>, in 2003. He said he could understand if NASA officials \u201ccircled the wagons\u201d in response to the IRT\u2019s work, but he said the agency could not have been more forthcoming. Every time the review team wanted more data or information, it was made available. Eventually, this made the entire IRT comfortable with NASA\u2019s findings.<\/p>\n The stickiest point during the review team\u2019s discussions involved the permeability of the heat shield. Counter-intuitively, the heat shield was not permeable enough during Artemis I. This led to gas buildup, higher pressures, and the cracking ultimately observed. The IRT was concerned because, as designed, the heat shield for Artemis II is actually more<\/em> impermeable than the Artemis I vehicle.<\/p>\n Why is this? It has to do with the ultrasound testing that verifies the strength of the bond between the Avcoat blocks and the titanium skin of Orion. With a more permeable heat shield, it was difficult to complete this testing with the Artemis I vehicle. So the shield for Artemis II was made more impermeable to accommodate ultrasound testing. \u201cThat was a technical mistake, and when they made that decision they did not understand the ramifications,\u201d Hill said.<\/p>\n However, Hill said NASA\u2019s data convinced the IRT that modifying the entry profile for Artemis II, to minimize the duration of passage through the atmosphere, would offset the impermeability of the heat shield.<\/p>\n Hill said he did not have the authority to release the IRT report, but he did agree that the space agency has not been forthcoming with public information about their analyses before this week.<\/p>\n \u201cThis is a complex story to tell, and if you want everybody to come along with you, you\u2019ve got to keep them informed,\u201d he said of NASA. \u201cI think they unintentionally did themselves a disservice by holding their cards too close.\u201d<\/p>\n","protected":false},"excerpt":{"rendered":" Within hours of NASA announcing its decision to fly the Artemis II mission aboard an Orion spacecraft with an unmodified heat shield, critics assailed the space agency, saying it had made the wrong decision. \u201cExpediency won over safety and good materials science and engineering. Sad day for NASA,\u201d Ed Pope, an expert in advanced materials […]<\/p>\n","protected":false},"author":1,"featured_media":44569,"comment_status":"","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"inline_featured_image":false,"footnotes":"","_links_to":"","_links_to_target":""},"categories":[2],"tags":[7856,640,21],"class_list":["post-44566","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-news","tag-heat-shield","tag-orion","tag-space"],"acf":[],"_links":{"self":[{"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/posts\/44566"}],"collection":[{"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/comments?post=44566"}],"version-history":[{"count":0,"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/posts\/44566\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/media\/44569"}],"wp:attachment":[{"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/media?parent=44566"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/categories?post=44566"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/tags?post=44566"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}Publicly, NASA could have been more transparent<\/h2>\n